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Isolating the Impact of Dimensionality on Bandit Regret via Fixed-Gap Gaussian Environments

2026 · Proceedings of the 4th International Conference on Image, Algorithms, and Artificial Intelligence, ICIAAI 2026, 22-24 May 2026, Singapore, Singapore · 0 citations · 8 references

TL;DR

It is suggested that standard strategies need structural changes, like subsampling, to work efficiently in large-scale environments to handle a massive number of sub-optimal arms.

Abstract

. This study tests how Explore-Then-Commit (ETC), Upper Confidence Bound (UCB), and Thompson Sampling (TS) behave in a static setting where the action space size, K, varies from 10 to 2,400. A Fixed-Gap Gaussian Environment based on MovieLens data is used to ensure the task difficulty stays the same. Experiments show that performance gets worse for every algorithm as K increases. ETC fails the most, with identification accuracy dropping below 20% because it wastes too much budget on exploration. UCB and TS do better but still show linear regret growth. This implies that probabilistic exploration is not enough to handle a massive number of sub-optimal arms. The findings suggest that standard strategies need structural changes, like subsampling, to work efficiently in large-scale environments.

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